1. Field of the Invention
This invention relates to a laminated molding which absorbs striking energy due to collision, falling, etc. and displays shock-absorbing effects, and a method for producing the same.
2. Description of the Prior Art
In the collision of automobiles and travelling vehicles, cushioning articles giving shock-absorbing effects absorb the striking energy, functioning as protectors for the machine bodies or the operators.
Cushioning articles having been conventionally used are those formed by laminating a resinous foam on the surface of a structural member, metallic tubes or plates bent or folded in the form of helical springs or bellows, or cylinder-like cushioning devices making use of air pressure or oil pressure.
A metallic cushioning article, cylinder-like cushioning device or helical spring is used in fixing equipment by the cushioning matter itself, for example, in fixing and holding a handle and a shaft. In the case of using a metallic cushioning article, it is necessary to impart a feature to the configuration of its bending or folding section where the energy is absorbed. Further, the structure of the bending or folding section is complicated and its molding is difficult. On the other hand, the cylinder-like cushioning device has a defect in its heavy weight, while the helical spring is faulty in that it accumulates striking energy but releases the energy upon collision to destroy the collided object.
Further, an attempt has been made to use a molding obtained by laminating resinous plates of 0.05 to 1 mm thick, which have been prepared by impregnating 20% by volume or more of a reinforcing fiber with a thermoplastic resin, and molding the resultant laminate. In this case, the molding is lighter in weight than the metallics so that it has been used in a variety of applications as a lightweight cushioning article. However, the molding has involved such problems that it has a lower modulus of elasticity than the metallics so that it is broken by small deformation and absorbs less striking energy.
Therefore, when an impact force over the critical strain of a laminated molding is applied, the laminated molding is broken and fails to buffer the impact force satisfactorily. Since conventional laminated moldings produce a small degree of elastic deformation, they are difficult to buffer a large impact force and hence cannot cope with a wide range of impact forces.